DESCRIPTION: The goal of this proposal is to understand the nature of transcription factor binding, apoptosis and the role of Nef and Nef-binding proteins in the avoidance of killing by MHC class I-restricted CTLs. The role of Nef in down regulating MHC class I expression will be assessed using techniques that allow characterization by flow cytometric analysis of events in primary and cultured cells with high-titered mutant or wild-type viruses.